The invention relates to a milk pumping apparatus for vacuum milking installations for the withdrawal of milk from a milk receiver that is constantly under a vacuum to atmospheric pressure, while the milk receiver is connected with a milk releaser by a milk outlet line having a clack valve, and the milk releaser has a float which, when the milk releaser is full of milk, operates valves which shut off a vacuum line connecting the milk releaser to the milk receiver and open a line leading to the external atmosphere.
A milk pumping apparatus of this kind is generally known in which the milk is withdrawn from the milk releaser to bulk milk tanks or pipes which are under atmospheric pressure.
To prevent vacuum losses in milking, the milk produced at the milk stalls is carried in modern milking installations through milk collecting pipes to a receiver which is normally situated below the floor of the milking stall, the milk having to be pumped to bulk tanks situated at a higher elevation and farther away.
German Offenlegungsschrift No. 2,426,458 discloses a milk pumping apparatus in which a float is provided in the milk releaser connected to the outlet from the milk receiver, and when the milk releaser is filled with milk, the float opens a valve from the vacuum line to the receiver, and at the same time opens a second valve connected to a compressed air line. In this system, the milk releaser, which at first is under vacuum, is filled with air under pressure, whereupon the clack valve disposed in the drain line from the milk receiver is closed and the clack valve in the outlet from the milk releaser is opened. The milk is pumped to tanks situated at higher levels according to the amount of pressure in the milk releaser.
A disadvantage of this process is, however, the necessary supply of compressed air, which has to be produced by an air compressor.
Likewise, it is common to pump the milk to higher and more remote bulk tanks by means of an electric pump, and a filter is also frequently provided between the pump and the bulk tank to filter the milk.